The invention relates to an arrangement for the winding of a double yarn formed by two yarn components prestrengthened by means of pneumatic false-twist spinning onto a cross-wound spool in a spinning machine, having a yarn feeding device for the feeding of the double yarn, a traverse motion guide device cross-winding the double yarn on a cross-wound spool, and a driving device for driving the cross-wound spool.
It is known from European Patent Application (EP-A) Publication No. 38 143 to prestrengthen two slivers, that were drawn or drafted by means of a drafting roller device to a desired yarn count, by means of pneumatic false-twist spinning and to subsequently wind them as a double yarn onto a cross-wound spool. The two yarn components have an only relatively low strength. They receive the final strength that is required for the further processing by means of the fact that the double yarn is subsequently twisted together.
When producing cross-wound spools from yarn components of only prestrengthened slivers, certain problems arise. In order to produce a cross-wound spool, a side traverse motion of the double yarn is required, in which case the path of the yarn becomes periodically shorter and longer. When normally strengthened yarns are spun, these changes of length play no important role because they are absorbed by the elastic stretching of the yarns. In many cases, a yarn can therefore be wound up without any additional measures. In other cases, simple balancing structures sufficient that are arranged in a stationary or elastic way. However, in the case of only prestrengthened slivers, these changes of length may result in an additional periodic stretching and thus in a remaining periodic change of length which is connected with yarn defects. It is therefore necessary to proceed with the prestrengthening to such an extent that a certain elastic stretching in the prestrengthened yarns is necessary. However, this degree of prestrengthening is not required for the twisting process that follows because the double yarn in this case is not subjected to similar stress.
An objective of the invention is to develope an arrangement of the initially mentioned type in such a way that changes in the path of the yarn are avoided during the winding-up at a cross-wound spool.
This objective is achieved according to the invention by providing a yarn path deflecting device between the feeding device and the cross-winding device. The yarn path deflecting device is arranged to move synchronously, but out-of-phase with respect to the cross-winding device so as to deflect the double yarn with a to-and-fro motion in such a way that always an approximately equally long path for the double yarn exists between the feeding device and the cross-winding device. By these measures, changes of length during the winding-up are reliably avoided so that less prestrengthening of the yarn components is required and thus a higher production speed can be used, without increasing the danger of yarn breakages to an inadmissible degree.
In a further development of certain preferred embodiments of the invention, it is provided that the cross-winding device and the deflecting device are connected to the same drive. As a result, it is ensured that the synchronous movement between the two devices is constantly guaranteed.
In a further development of certain preferred embodiments of the invention, it is provided that the deflection device moves in a plane that is offset by 90.degree. with respect to the plane in which the cross-winding device moves. In a further development, it is provided in this case that the deflecting device, starting from the shortest yarn deflection, moves only toward one side and with a frequency that is twice as high as the frequency of the movement of the cross-winding device.
Although it is known from German Patent (DE-PS) No. 24 54 917 to provide, between a feeding device and a wind-up device, a swing lever as the yarn-balancing device that is forcibly coupled with the cross-winding of the yarn, this swing lever has the purpose of being able to Produce conical cross-wound spools in which case different spool diameters exist and as a result different winding speeds. This device that is intended for the winding-up of normally strengthened yarns cannot be applied to the winding-up of double yarns consisting of only prestrengthened yarn components.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.